using System;
using System.Diagnostics.Contracts;
using System.Globalization;
using System.Windows;
using System.Windows.Data;

namespace OpenLS.Drawing.UI.Internals
{
    ///<summary>
    /// Specifies whether an instance is of a given type
    ///</summary>
    public class IsOfTypeConverter : IValueConverter
    {
        #region IValueConverter Members

        /// <summary>
        /// Converts a value. 
        /// </summary>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        /// <param name="value">The value produced by the binding source.
        ///                 </param><param name="targetType">The type of the binding target property.
        ///                 </param><param name="parameter">The converter parameter to use.
        ///                 </param><param name="culture">The culture to use in the converter.
        ///                 </param>
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (targetType == typeof(bool) || targetType == typeof(object))
            {
                if (value == null)
                    return false;
                var type = parameter as Type;
                if (type == null)
                {
                    // Contract.Assert(false);
                    return false;
                }
                return type.IsAssignableFrom(value.GetType());
            }

            bool b = (bool)Convert(value, typeof(bool), parameter, culture);
            if (b)
                return Visibility.Visible;
            return Visibility.Collapsed;
        }

        /// <summary>
        /// Converts a value. 
        /// </summary>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        /// <param name="value">The value that is produced by the binding target.
        ///                 </param><param name="targetType">The type to convert to.
        ///                 </param><param name="parameter">The converter parameter to use.
        ///                 </param><param name="culture">The culture to use in the converter.
        ///                 </param>
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotSupportedException();
        }

        #endregion

    }
}